This invention relates to a printer, and more particularly to an improvement in a sheet handler for a printer.
In general, a printer discharges printed sheets with the printed surfaces upwards. This sheet discharging method is disadvantageous when a number of sheets are printed, discharged and stacked. In the stack, the sheet printed first is at bottom, and the sheet printed last is at top. Hereinafter, this stacking order will be referred to as a "reverse stacking order", when applicable.
The stacking of printed sheets in the reverse stacking order is not preferable or convenient when, for instance, when a number of sheets are printed with serial or page numbers, as they should be stacked on one another so that the sheet printed first is at top and the sheet printed last is at bottom. In other words, they should be in the forward stacking order instead of the opposite reverse stacking order.
This difficulty can be eliminated by employing a method of discharging the printed sheets from the printer with the printed surfaces downwards. More specifically, in this method, each printed sheet is turned over when discharged from the printer. In order to practice this method, a printer has been proposed in the art which has a U-shaped guide plate downstream of a printed sheet discharging roll in order to turn the printed sheets over. However, this type of printer has a problem in that sometimes the surface of the guide plate is rubbed and a printed sheet is caught making it impossible to smoothly turn the sheet over.
On the other hand, if printed sheets are discharged from the printer with the printed sides downwards, then it is impossible to observe the printed sides, and accordingly it is rather difficult to control print density. Hence, in general, the printed sheets are discharged from the printer with the printed sides upwards.